Percutaneous spinal cross link system and method

ABSTRACT

A percutaneous spinal cross link system for interconnecting a spinal fusion construct on one side of the longitudinal axis of the spine with a spinal fusion construct on the other side of the longitudinal axis may include a cross bar connected at each end by a respective connector to a respective spinal fusion rod of each of the spinal fusion constructs. The connector may include a rod receiving portion adapted to receive one of the spinal fusion rods and a cross bar receiving portion adapted to receive the cross bar in an orientation generally perpendicular to the spinal fusion rod. A cannula defined by two spaced apart blades may be connected to the connector for defining a minimally invasive pathway through body tissue for introduction of the cross bar to the connector. Other tools for use with the system are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/201,213, filed on Mar. 7, 2014, which application claims the benefitof the filing date of U.S. Provisional Patent Application No. 61/782,278filed Mar. 14, 2013, the disclosures of which are hereby incorporatedherein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to the percutaneous insertion of spinalfusion implants into the body of a patient and the affixation of thoseimplants to the spine.

Pedicle screw fixation constructs have been in use for decades in orderto fuse adjacent vertebral segments to improve spinal stability orcorrect certain spinal deformities. Older approaches for inserting thesefixation constructs involved open procedures, in which relatively largeskin incisions were created to expose a substantial portion of thepatient's spinal column, in order to allow for insertion of the pediclescrews and manipulation of spinal rods through openings in pediclescrews, such openings typically being in heads of the screws.

Over time, less invasive approaches have been developed. Typically, insuch approaches, pedicle screws are inserted into the pedicles ofadjacent vertebrae of a patient's spine through individual percutaneousincisions corresponding to the pedicle screws. Fixation or fusion rodsare then inserted into the body through one of those incisions, orthrough an additional incision adjacent to the most cephalad or caudalpedicle screw, and the rod is rigidly connected to the heads of thepedicle screws such that the rod extends along the longitudinal axis ofthe spine (i.e., along the cephalad/caudal direction) in order to fixthe relative positions of the adjacent vertebrae to which the rod isconnected. In some such minimally invasive procedures, a percutaneousaccess device (e.g., a cannula or portal) is connected to each of thepedicle screws and extends through the respective percutaneous incision.Such percutaneous access devices provide a pathway through the tissuefrom each incision to the respective pedicle screw, in order to aid inthe insertion of a spinal rod. Examples of such percutaneous accessdevices are described in commonly-assigned U.S. Pat. No. 7,955,355 (“the'355 patent”) and U.S. Pat. No. 8,002,798 (“the '798 patent”), theentireties of which are hereby incorporated by reference herein as iffully set forth herein.

Although considerable effort has been devoted in the art to optimizationof such minimally invasive systems, still further improvement would bedesirable.

BRIEF SUMMARY OF THE INVENTION

One aspect of the present invention provides a connector for securing across bar to a spinal fusion construct. The connector according to thisaspect of the invention desirably includes a rod receiving portion and across bar receiving portion. The rod receiving portion is desirablyadapted to receive a spinal fusion rod of a spinal fusion constructtherein, and the cross bar receiving portion desirably has a receptacletherein. The receptacle of the cross bar receiving portion is desirablyadapted to receive a cross bar therein in an orientation generallyperpendicular to the spinal fusion rod when the spinal fusion rod isreceived within the rod receiving portion.

According to one aspect of the invention, the receptacle of the crossbar receiving portion is preferably defined between a first arm and asecond arm. According to another aspect of the invention, the armspreferably include inwardly facing threads along at least a portion ofthe receptacle, and the receptacle is preferably adapted to receive athreaded blocker in engagement with the threads. According to a furtheraspect of the invention, the rod receiving portion of the connectorpreferably includes a slot adapted to receive the spinal fusion rodtherethrough, and the slot is preferably defined between a first arm anda second arm. According to yet a further aspect of the invention, thefirst and second arms defining the slot are preferably adapted todeflect relative to one another when the spinal fusion rod is insertedinto the slot.

Further aspects of the invention provide a connector assembly forsecuring a cross bar to a spinal fusion construct. The connectorassembly according to this aspect of the invention desirably includes acannula and also desirably includes a connector in accordance with anyof the aspects of the invention described above. A distal end of thecannula is desirably connected to the connector such that a proximal endof the cannula extends through an incision in the skin of a body of apatient when the spinal fusion rod is received within the rod receivingportion of the connector and when the spinal fusion construct isimplanted in a spine of the patient.

According to one aspect of the invention, the cannula is preferablydefined by a plurality of blades, each of which preferably has a distalend detachably connected to the cross bar receiving portion of theconnector. According to another aspect of the invention, the blades arepreferably each integrally formed with the cross bar receiving portionof the connector and detachably connected thereto at a frangibleportion. According to yet another aspect of the invention, the cannulapreferably includes an inner surface having threads for engaging athreaded blocker along at least a distal portion of the cannula.

Yet further aspects of the invention provide a system for securing across bar to a spinal fusion construct. The system according to thisaspect of the invention desirably includes a dilator and also desirablyincludes a connector assembly in accordance with any of the aspects ofthe invention described above. The dilator is desirably adapted todefine a pathway between the incision in the skin of the patent and thespinal fusion rod of the spinal fusion construct implanted in the spine.The pathway is desirably adapted to receive the connector assemblythrough it.

According to one aspect of the invention, the system preferably includesa connector inserter having a shaft, the distal end of which ispreferably adapted to engage the cross bar receiving portion of theconnector while the shaft is received within and extends along thecannula of the connector assembly.

According to another aspect of the invention, the system preferablyincludes a linkage and also preferably includes a plurality of theconnector assemblies in accordance with any of the aspects of theinvention described above. According to this aspect of the invention,the linkage is preferably adapted to simultaneously connect to theproximal end of each of the cannulas of the connector assemblies whilethe spinal fusion rod is received within the rod receiving portions ofthe connectors and while the spinal fusion construct is implanted in aspine of the body.

According to another aspect of the invention, the system preferablyincludes a drill having an elongated extender. According to this aspectof the invention, the elongated extender is preferably adapted to bereceived within the cannula of the connector assembly. A distal end ofthe extender is preferably connected to a drill bit such that the drillbit extends generally perpendicularly to the extender.

According to another aspect of the invention, the system preferablyincludes a cross bar inserter, the distal end of which preferably has aconnection structure operable to selectively secure and release thecross bar to it. According to yet another aspect of the invention, thesystem preferably includes a persuader having a tubular member adaptedto receive the cannula of the connector assembly inside of it.

According to another aspect of the invention, the cannula of theconnector assembly is preferably defined by a plurality of blades.According to this aspect of the invention, each of the blades ispreferably integrally formed with the cross bar receiving portion of theconnector. Each of the blades also preferably has a distal enddetachably connected to the cross bar receiving portion of the connectorat a frangible portion. The system preferably includes a blade removerhaving a channel adapted to receive one of the blades.

Yet further aspects of the invention provide a method for securing across bar to a spinal fusion construct. The method according to thisaspect of the invention desirably includes forming a minimally invasivepathway between an incision in the skin of a patient and a spinal fusionrod of a spinal fusion construct implanted in a spine of the patient.The method desirably also includes passing a connector through thepathway and attaching the connector to the spinal fusion rod. Theconnector desirably has a cross bar receiving portion adapted to receivea cross bar therein in an orientation generally perpendicular to thespinal fusion rod.

According to one aspect of the invention, the method preferably includesmaintaining the minimally invasive pathway with a first cannula, thedistal end of which is preferably connected to the cross bar receivingportion of the connector. According to another aspect of the invention,the method preferably includes inserting the cross bar into the body ofthe patient along the first cannula and through a slot along the firstcannula.

According to another aspect of the invention, the method preferablyincludes advancing the cross bar towards the cross bar receiving portionof the connector. Such advancement is preferably performed by rotatablyadvancing a threaded blocker along a threaded portion of the firstcannula.

According to another aspect of the invention, the method preferablyincludes detaching a plurality of blades defining the first cannula fromthe cross bar receiving portion of the connector. According to a furtheraspect of the invention, the step of detaching the blades preferablyincludes breaking the blades away from the cross bar receiving portionof the connector.

According to another aspect of the invention, the method preferablyincludes forming a second minimally invasive pathway between a secondincision in the skin of the patient and a second spinal fusion rod ofthe spinal fusion construct. The method according to this aspect of theinvention preferably also includes passing a second connector throughthe second pathway and attaching the second connector to the secondspinal fusion rod. The second connector preferably has a cross barreceiving portion which is adapted to receive the cross bar therein inan orientation generally perpendicular to both the spinal fusion rod andthe second spinal fusion rod. The method according to this aspect of theinvention preferably also includes maintaining the second minimallyinvasive pathway with a second cannula, the distal end of which ispreferably connected to the cross bar receiving portion of the secondconnector.

According to another aspect of the invention, the method preferablyincludes attaching a linkage to the proximal ends of the first andsecond cannulas. According to a further aspect of the invention, themethod preferably includes forming an opening in a spinous process ofthe spine with a drill which is inserted along the minimally invasivepathway.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a portion of a spine with a prior artspinal fusion construct connected thereto.

FIG. 2 is a perspective view of a construct of spinal fusion systemcomponents in accordance with aspects of the present invention.

FIGS. 3A-B are perspective views of components of a dilation system inaccordance with an embodiment of the present invention.

FIG. 3C is a perspective view of an assembly of the components of FIGS.3A and 3B.

FIG. 4A is a perspective view of a portion of a prior art spinal fusionconstruct having a percutaneous access device connected thereto.

FIG. 4B is a perspective view of a component of a dilation system inaccordance with another embodiment of the present invention assembledwith the portion of the spinal fusion construct of FIG. 4A.

FIG. 5 is a perspective view of two integrated connectors in accordancewith embodiments of the present invention.

FIGS. 6A-B are sectional views of portions of an integrated connector ofFIG. 5.

FIG. 7A is a perspective view of an integrated connector of FIG. 5assembled with a connector inserter in accordance with an embodiment ofthe present invention.

FIG. 7B is an enlarged view of a portion of the assembly of FIG. 7A.

FIG. 8 is a perspective view of a plurality of the integrated connectorsof FIG. 5 assembled with a portion of a spinal fusion construct inaccordance with an embodiment of the present invention.

FIG. 9 is a perspective view of a linkage assembled with integratedconnectors in accordance with an embodiment of the present invention.

FIG. 10 is a perspective view of a right-angle drill in accordance withan embodiment of the present invention.

FIGS. 10A-B are perspective views of a portion of the right-angle drillof FIG. 10 in two different configurations.

FIG. 11A is a perspective view of a portion of a cross bar inserterconnected to a cross bar in accordance with an embodiment of the presentinvention.

FIG. 11B is a perspective view of a method of insertion of a cross barinto the assembly of FIG. 8.

FIG. 12A is a perspective view of a method of persuading the cross barinto the assembly of FIG. 8.

FIG. 12B is a perspective, sectional view of the method of FIG. 12A.

FIG. 13 is a perspective view of a method of removing the blades fromthe integrated connectors of the assembly of FIG. 8.

DETAILED DESCRIPTION

Where reference is made herein to directional terms such as “proximal,”“proximal most,” “distal,” and “distal most,” it is to be understoodthat “proximal” and “proximal most” refer to locations closer to a useror operator of the device or method being described and that “distal”and “distal most” refer to locations further from a user or operator ofthe device or method being described.

Referring to FIG. 1, a perspective view illustrates a portion of a spine10. FIG. 1 illustrates only the bony structures; accordingly, ligaments,cartilage, and other soft tissues are omitted for clarity. The spine 10has a cephalad direction 12, a caudal direction 14, an anteriordirection 16, a posterior direction 18, and a medial/lateral axis 20,all of which are oriented as shown by the arrows bearing the samereference numerals. In this application, “left” and “right” are usedwith reference to a posterior view, i.e., a view from behind the spine10. “Medial” refers to a position or orientation toward a sagittal plane(i.e., plane of symmetry that separates left and right sides from eachother) of the spine 10, and “lateral” refers to a position ororientation relatively further from the sagittal plane.

As shown, the spine 10 illustrated in FIG. 1 includes a first vertebra22, a second vertebra 24, and a third vertebra 26. Connecting elements30 of a spinal fusion construct are connected to respective pedicles 36,38, 40 on the right side of the respective first, second, and thirdvertebrae 22, 24, 26. The connecting elements 30 each include a pediclescrew (not shown) implanted in the respective pedicles 36, 38, 40 and acage 42 for receiving a spinal fusion rod 44 therein. The cages 42 maybe polyaxially coupled to the respective pedicle screws. Each connectingelement 30 may also include a set screw 45 for securing the rod 44within the cage 42. The connecting elements 30 may have the samestructure as the connecting elements described in the '798 patent, andthe connecting elements 30 and the rod 44 may have been percutaneouslyinserted in the same manner as described in that patent. That is, theconnecting elements 30 may have been inserted through separate incisionswith the help of guide wires and/or dilators, and the rod 44 may havebeen inserted with the help of cannulas secured to the connectingelements 30.

Although only one construct on one side (i.e., the right side) of thespine 10 is illustrated in FIG. 1, another similar spinal fusionconstruct could be connected to pedicles on the other side of the spinein a similar manner, such that the rods 44 extend generally parallel toone another along the longitudinal axis of the spine. As shown in FIG.2, a construct in accordance with the present invention may include aplurality of connecting elements 30 a with an associated rod 44 aextending generally parallel to a plurality of connecting elements 30 bwith an associated rod 44 b. Although the spine is not illustrated inFIG. 2, the construct illustrated in FIG. 2 would preferably beconnected to the spine such that the pedicle screws 32 a of connectingelements 30 a would be implanted in pedicles on one side of thelongitudinal axis of the spine and the pedicle screws 32 b of theconnecting elements 30 b would be implanted in pedicles on the otherside of the longitudinal axis of the spine, such that the rods 44 a and44 b extend generally parallel to the longitudinal axis of the spinewith the spinous processes of the spine extending between the rods 44 aand 44 b.

In accordance with embodiments of the present invention, cross links 46may extend between and be connected to both rods 44 a and 44 b.Desirably such cross links 46 help to stabilize and increase rigidity ofthe spinal fusion construct. The cross links 46 may include connectors48 secured to each rod 44 a,b and cross bars 50 received within andsecured to the connectors 48 by blockers 52, as discussed in more detailbelow. A system and method for percutaneously installing such crosslinks 46 into a spinal fusion construct follows below.

After two generally parallel constructs of connecting elements 30 androds 44 have been installed on each side of the spine, for example withthe systems and methods described in the '798 patent, the cross links 46may then be installed. First, the surgeon may determine at whichlocations along the rods 44 the cross links 46 are to be located.Although the connectors 48 of the present invention are desirablystructured so as to be positionable at any location along the rods 44,in some preferred spinal fusion constructs in accordance with thepresent invention the connectors 48 may be located close to theconnecting elements 30. It is believed that such placement of the crosslinks 46 may increase the stability of the spinal fusion construct.

After the desired locations for the connectors 48 have been determined,the body tissue between the skin and each of those locations may bedilated. In one embodiment, the dilation may be performed by inserting adilation system including a generally tubular dilator 54, as shown inFIG. 3A, through an incision in the skin to the desired location alongthe rod 44. The dilator 54 has a proximal end 56 and a distal end 58 anddefines a passageway 57 therealong. The distal end 58 may have anattachment portion 60 for attachment to the rod 44. For example, theattachment portion 60 may include a recess 62 shaped to receive at leasta portion of the rod 44 therein. As shown in FIGS. 3A and 3C, the recess62 may be partially cylindrical and open to the distal end 58 to receivethe rod 44. In order to provide a more stable connection to the rod 44,the attachment portion 60 may be structured to snap onto the rod 44 bydeforming when the rod 44 is received within the recess 62. In such anembodiment, a slot 64 may be provided to facilitate such deformation. Toease the insertion of the dilator 54, in some embodiments of thedilation system, a pathway between the skin incision and the desiredlocation along the rod 44 may be sequentially dilated by a series ofsuccessively larger dilators inserted one over another, for example asdiscussed in the '798 Patent, after which the dilator 54 may be insertedover the last of such dilators. In other embodiments of the dilationsystem, a single inner dilator 66, as shown in FIG. 3B, may be insertedalong the pathway, after which the dilator 54 may be inserted over theinner dilator 66, as shown in FIG. 3C. The inner dilator 66 may begenerally tubular structure sized to be closely received within thedilator 54 and having a proximal end 68 and a distal end 70. In someembodiments, the distal end 70 may be tapered, as shown in FIG. 3B, inorder to gently spread the tissue apart along the pathway as the innerdilator 66 is inserted.

Another embodiment of a dilation system may include a dilator 72, asshown in FIG. 4B, which may be structured to engage a percutaneousaccess device connected to one of the connecting elements 30. Thepercutaneous access device may be in the form of those described in the'355 patent and the '798 patent. For example, as shown in FIG. 4A, thepercutaneous access device may be a cannula 74 defined by a two blades76 connected to opposing sides of the cage 42. The blades 76 may beseparately formed from and detachably connectable to the cage 42 of theconnecting element 30 by a distal tab 80, as described in certainembodiments of the '798 patent. Alternatively, the cannula 74 may bedefined by blades that are integrally formed with the cage 42 andconnected thereto by frangible portions (e.g., reduced thicknessportions, which may be defined by grooves formed in either or both ofthe interior and exterior surfaces of cannula at the junction betweenthe blades and the cage), whereby the blades are detachable from thecage 42 breaking the blades away from the cage 42 at the frangibleportions. As shown in FIG. 4B, the dilator 72 has a proximal end 81 anda distal end 83 and defines a passageway 85 therealong, and the dilator72 may include a generally tubular cannula 82 and an attachmentstructure 84 constructed to engage the blades 76. The attachmentstructure 84 may include a plurality of receivers 86 extending laterallyfrom the cannula 82, each of the receivers 86 having a channel 88therealong shaped to receive one of the blades 76 therein. The dilator72 may be inserted into the body by inserting the proximal ends 90 ofthe blades 76 into the channels 88 of the receivers 86 at the distal end83 of the dilator and advancing the dilator 72 distally through the bodytissue. During the advancement, the cannula 82 of the dilator may firstpass through an incision in the skin, such as an incision adjacent tothe cannula 74 defined by the blades 76, and then may progress distallythrough the body tissue to a desired location along the rod 44, such asa location adjacent to the cage 42. To ease the insertion of the dilator72, in some embodiments of the dilation system, a pathway between theskin incision and the desired location along the rod 44 may be dilatedin advance of the movement of the cannula 82 along that pathway. Forexample, a dilator (not shown) having a tapered distal end, such as adilator structured similarly to the inner dilator 66 of FIG. 3B, may beinserted along the pathway in advance of the cannula 82. In one example,such a dilator may be received within the passageway 85 of the cannula82 with the tapered distal end of the dilator projecting distally of thecannula 82 so as to gently spread the tissue apart along the pathway asthe dilator 72 is inserted.

The body tissue between the skin and each of the desired locations forthe connectors 48 may be dilated using one or a combination of dilationsystems, such as those illustrated in FIGS. 3A-C and 4B. In order toprepare for the insertion of the connectors 48 along the pathwaysdefined by those dilation systems, one or more tools may be used to pushtissue away from the desired locations for the connectors 48. Forexample, an elongate tool (not shown) may be inserted along thepassageways 57, 85 defined by the dilators 54, 72, and the distal end ofsuch tool may be used to push any tissue away from the desired locationsfor the connectors 48. The connectors 48 may then be inserted along thepassageways 57, 85 to the desired locations along the rods 44.

In one embodiment of the present invention, the connectors 48 may beinitially connected to a percutaneous access device before placementwithin the body. For example, as illustrated in FIG. 5, the percutaneousaccess device may be in the form of a cannula 92 defined by a two blades94 extending proximally from opposing sides of the connector 48. In theembodiment illustrated in FIG. 5, the blades 94 may be integrally formedwith the connector 48 and connected thereto by frangible portions 96 atthe distal end 97 of the cannula 92, thus forming an integratedconnector 98 having a proximal end 101 and a distal end 103, with theconnector 48 being located at the distal end 103 of the integratedconnector 98. However, in an alternative embodiment, the blades 94 maybe separately formed from and detachably connectable to the connector48, such as by distal tabs, as described in certain embodiments of thepercutaneous access devices in the '798 patent. The blades 94 may definea pass-through slot 100 extending between them. In other embodiments(not shown), the percutaneous access device may define a slot openingradially outward in only one direction along the cannula 92. In someembodiments, a separately formed ring 102 may be connected to bothblades 94, preferably towards the proximal end 99 of the cannula 92, soas to stabilize the blades 94 and resist their becoming detached fromthe connector 48 prematurely. The ring 102 may be shaped as an annularmember having channels formed therethrough for receiving the blades 94therein. In certain embodiments, the ring 102 may be in the form ofabutment member as described in the '798 patent. The ring 102 may beconnected to the blades 94 before the integrated connector 98 isinserted into the body or after the integrated connector 98 is connectedto the rod 44 within the body.

The connector 48 may include a connecting member 104 and a retainingmember 106. The retaining member 106 may be in the form of a separatelyformed ring encircling a portion of the connecting member 104. FIG. 6Ais a cross-sectional view of a portion of an integrated connector 98towards its distal end 103 with the retaining member 106 removed, thecross-section being taken along a plane perpendicular to the slot 100.The connector 48 includes a rod receiving portion 108 for receiving arod 44 and a cross bar receiving portion 110 for receiving a cross bar50. The cross bar receiving portion 110 may include two proximallyextending arms 112 defining a receptacle 114 therebetween shaped toreceive a cross bar 50 therein in an orientation perpendicular to thelongitudinal axis 116 of the integrated connector 98. The receptacle 114may be in form of a pass through slot communicating with the slot 100 ofcannula 92 at the distal end 97 of the cannula 92. The cannula 92 mayinclude a threaded portion 118 at least along the distal end 97 thereof,and the cross bar receiving portion 110 of the connector 48 may includea threaded portion 120 along the arms 112 thereof. In other embodiments(not shown), the threaded portion 118 of the cannula 92 may not bepresent while the threaded portion 120 of the connector 48 is present.The arms 112 of the cross bar receiving portion 110 may each beconnected to a respective one of the blades 94 at one of the frangibleportions 96. The frangible portions 96 may be defined by reducedthickness portions, such as by one or both of interior grooves 122 andexterior grooves 124. The interior and exterior grooves 122, 124 may besubstantially aligned with one another along the longitudinal axis ofthe integrated connector 98, as shown in FIG. 6A, to define the reducedthickness portion of the frangible portion 96.

FIG. 6B is a cross-sectional view of a portion of an integratedconnector 98 towards its distal end 103 with the retaining member 106removed, the cross-section being taken along a plane parallel to theslot 100 and perpendicular to the view of FIG. 6A. The view of FIG. 6Bfocuses on the rod receiving portion 108 of the connector 48. The rodreceiving portion 108 may include two distally extending arms 126defining a receptacle 128 therebetween shaped to receive a rod 44therein in an orientation perpendicular to the longitudinal axis 116 ofthe integrated connector 98 and generally perpendicular to theorientation of the cross bar 50 when the cross bar 50 is received withinthe cross bar receiving portion 110 of the connector 48. The receptacle128 may be in form of a pass through slot open to the distal end 103 ofthe integrated connector 98. The rod receiving portion 108 may bestructured to snap onto the rod 44 by deforming when the rod 44 isinserted into the receptacle 128. For example, the arms 126 may deflectaway from one another during such insertion. One or more slots 130extending further into the rod receiving portion 108 from the receptacle128 may be provided to facilitate such deflection of the arms 126. Theopening 132 into the receptacle 128 at the distal end 103 of theintegrated connector 98 may also have a chamfer 134 to ease insertion ofthe rod 44 into the receptacle 128 and initiate the deflection of thearms 126 during such insertion.

The retaining member 106 desirably provides stiffness to the connectingmember 104, such as by restraining the arms 126 from deflecting tooeasily. In that manner, the retaining member 106 desirably helps tosecure the connector 48 to the rod 44 by restraining the rod 44 frombecoming dislodged from the receptacle 128 when not desired. Theretaining member 106, when engaged with and encircling the connectingmember 104, may engage the connecting member 104 along engagementsurfaces 136. As shown in FIG. 7B, the retaining member 106 may take theform of a generally annular ring encircling the connecting member 104.The retaining member 106 may include proximally-extending, arcuatedeviations 138 on opposing sides of the retaining member 106 and alignedwith the receptacle 128, so as to not interfere with a rod 44 placedinto and extending laterally through the receptacle 128.

A connector inserter 140, as illustrated in FIGS. 7A-B, may be engagedwith an integrated connector 98 in order to assist with the insertion ofthe integrated connector 98 along the passageways 57, 85 of the dilators54, 72 and to the desired locations along the rods 44. The connectorinserter 140 may have a proximal end 142 and a distal end 144 with anelongate shaft 146 extending therebetween, the shaft 146 beingconfigured to be received within the cannula 92 of the integratedconnector 98. The proximal end 142 of the connector inserter 140 mayinclude a handle 148, and the distal end 144 of the connector inserter140 may include a threaded portion 150 for engagement with the threadedportion 120 of the connector 48, as shown in FIG. 7B. The connectorinserter 140 may thus be engaged with the integrated connector 98 byadvancing the connector inserter 140 distally within the cannula 92 androtating the threaded portion 150 of the connector inserter 140 intoengagement with the threaded portion 120 of the connector 48. Theintegrated connector 98 may then be inserted into the body by graspingthe handle 148 of the connector inserter 140 and using the connectorinserter 140 to manipulate the integrated connector 98 down along theone of the passageways 57, 85 of the dilators 54, 72 until the rodreceiving portion 108 of the connector 48 snaps into engagement with therod 44. The connector inserter 140 may then be removed by rotating thethreaded portion 150 of the connector inserter 140 out of engagementwith the threaded portion 120 of the connector 48 and withdrawing theconnector inserter 140 proximally. After any of the integratedconnectors 98 are engaged with the rods 44, the associated dilators 54,72 may be removed. In some embodiments of the present invention, a ring102 (see FIG. 5) may be connected to the blades 94 of an integratedconnector 98 after the dilator 54, 72 has been removed, and, in otherembodiments, a ring 102 may be connected to the blades 94 before theintegrated connector 98 is inserted into the body through the dilator54, 72.

FIG. 8 illustrates two integrated connectors 98 connected to respectiverods 44 a,b adjacent respective cages 42 a,b of respective connectingelements 30 a,b. The cannulas 92 of the integrated connectors 98 thusdesirably provide percutaneous pathways through body tissue from theconnectors 48 to respective incisions in the skin. Although notillustrated in FIG. 8, the connecting element 30 a would be implanted ina pedicle on one side of the longitudinal axis of the spine, and theconnecting element 30 b would be implanted in a pedicle on the otherside of the longitudinal axis of the spine, such that the rods 44 a and44 b extend generally parallel to the longitudinal axis of the spinewith the spinous processes of the spine extending between the rods 44 aand 44 b. One of the cages 42 a in FIG. 8 is illustrated as having twoblades 76 of a cannula 74 of a percutaneous access device connectedthereto. The slots 100 of the integrated connectors 98 may be generallyaligned with one another and may extend generally perpendicular to therods 44 a,b.

In some embodiments, as shown in FIG. 9, a linkage 152 may be connectedto the proximal ends 101 of the integrated connectors 98 after theintegrated connectors 98 are connected to the respective rods 44 a,b.The linkage 152 may include a rail 154 having a movable link 156slidably connected thereto and having a fixed link 158 rigidly connectedto one end. The movable link 156 may have a locked and an unlockedconfiguration, such that the movable link 156 freely slides along therail 154 to vary the distance between the two links 156, 158 in theunlocked configuration, and such that the movable link 156 resistsmovement along the rail 154 in the locked configuration. The rail 154may include graduations 160 along its length, which graduations 160 maybe marked with measurements. Each link 156, 158 may be connected to theproximal end 101 of an integrated connector 98, as shown in FIG. 9, tostabilize the integrated connectors 98. The graduations 160 may alsohelp to determine the distance between the connectors 98, which mayassist with the determination of an appropriate length for a cross bar50 to be inserted between the connectors 48.

Before inserting a cross bar 50 between the connectors 48, a pathwaybetween the connectors 48 may first be created. For example, one or moreelongate tools (not shown) may be passed down through the cannulas 92 ofone or more of the integrated connectors 98 and through the slots 100 soas to separate or cut away tissue between the connectors 48. In somemethods, the spinous processes between the generally parallel rods 44 aand 44 b may interfere with the desired placement of a cross bar 50. Insuch cases, a portion of the interfering bone may be removed.

One exemplary tool for performing such bone removal, in accordance withan embodiment of the present invention, includes a right-angle drill 162as shown in FIG. 10. The right-angle drill 162 may have a proximal end166 and a distal end 168 and an elongated extender 164 extendingtherebetween. The distal end 168 of the right angle drill 162 may bestructured to sit stably within a receptacle 114 of a cross barreceiving portion 110 of a connector 48. A drill bit 172 may beconnected to a drill bit attachment mechanism 170 located at the distalend 168 of the right-angle drill 162. The drill bit attachment mechanism170 may be connected to the extender 164 by a right-angle bend 169, suchthat the drill bit 172 extends in a generally perpendicular direction tothe extender 164. The drill bit attachment mechanism 170 may bestructured for detachable connection to the drill bit 172. For example,as shown in FIG. 10A, the drill bit 172 may include a connection end 171structured for removable insertion into a receiver opening (not shown)in the drill bit attachment mechanism 170. After the connection end 171is positioned within the receiver opening, a locking lever 173 may bepivoted downwardly, as shown in FIG. 10B, to secure the drill bit 172within the drill bit attachment mechanism 170. The extender 164 of theright-angle drill 162 may be structured as a hollow shaft, so that adrive shaft (not shown) may be rotatably received within the extender164 for driving the rotation of the drill bit 172. The drive shaft maybe operably coupled to the drill bit 172 via a mechanism (not shown) fortransmitting the rotary motion of the drive shaft through theright-angle bend 169, such as a universal joint, a bevel gear, a wormgear, or any other suitable mechanism. The extender 164 may include oneor more holes 175 along its length, which holes 175 may communicate withthe interior of the extender 164 for cleaning or other purposes. Theproximal end 166 of the extender 164 may be connected to a drive handle174 for actuating the rotation of the drill bit 172. The drive handle174 may be detachably connected to a connector (not shown) at theproximal end 166 of the extender 164, which connector is operablycoupled to the drive shaft. In some embodiments, other types of drivehandles (e.g., drive handle 174′ illustrated in FIG. 10) may beinterchangeably connected to the connector at the proximal end 166 ofthe extender 164. The right-angle drill 162 may be structured such thatrotation of the drive handle 174 causes rotation of the drill bit 172(e.g., in a 1:1 ratio, although other ratios may be used). In otherembodiments (not shown), the right-angle drill 162 may incorporate amotor for electrical power driven rotation of the drill bit 172. Theright-angle drill 162 may include a support handle 176 located along theextender 164 between the proximal end 166 and the distal end 168. Thesupport handle 176 may extend in a generally perpendicular orientationfrom the extender 164.

In use, an appropriate drill bit 172 may first be connected to the drillbit attachment mechanism 170. For example, based on the approximatedistance between the connectors 48 indicated by the graduations 160 ofthe linkage 152, a drill bit 172 having an appropriate length may beconnected to the drill bit attachment mechanism 170. The right-angledrill 162 may then be inserted along a cannula 92 of one of theintegrated connectors 98, and the drill bit 172 may extend through aslot 100 of the integrated connector 98 towards a location on a spinousprocess where the surgeon desires an opening to be formed. Theright-angle drill 162 may be positioned such that, at least initially,the distal end 168 rests in the receptacle 114 of the cross barreceiving portion 110 of a connector 48. The drive handle 174 may thenbe rotated in order to rotate the drill bit 172 and form an openingthrough the spinous process. Fluoroscopy may be used to help navigatethe drill bit 172 within the body, and the perpendicularly extendingsupport handle 176 may be used both to support the right-angle drill 162and to act as a directional vector, as the support handle 176 maydesirably extend generally parallel to the drill bit 172. After one ormore openings are formed through one or more spinous processes with theright-angle drill 162, the right-angle drill 162 may be removed from thebody.

Before a cross bar 50 is inserted into the body and connected betweentwo connectors 48, the cross bar 50 may first be bent and/or cut asneeded so that the cross bar 50 is appropriately sized and shaped toextend between the connectors 48. The cross bar 50 may be attached to across bar inserter 178, as shown in FIGS. 11A-B, before insertion intothe body. The cross bar inserter 178 may be an elongate tool having ahandle 184 at a proximal end 180 and a connection structure 186 at thedistal end 182 for detachably connecting to a cross bar 50. The proximalend 180 of the cross bar inserter 178 may also include an actuator 188configured to operate the connection structure 186 so as to selectivelysecure and release the cross bar 50 to the connection structure 186.Once the cross bar 50 is attached to the cross bar inserter 178, thehandle 184 of the cross bar inserter 178 may be grasped and used tomanipulate the cross bar 50 down along the cannula 92 of one of theintegrated connectors 98, through the slot 100, and across through bodytissue (including through an opening in the spinous process, ifapplicable), as illustrated in FIG. 11B, until the cross bar 50 extendsbetween the integrated connectors 98 in a position proximate theconnectors 48 attached to each parallel rod 44 a,b.

Once the cross bar 50 is positioned proximate the connectors 48, thecross bar 50 may be moved into a final position extending between andsimultaneously received by the receptacles 114 of the cross barreceiving portions 110 of each of the connectors 48. The cross bar 50may be moved into that final position using the cross bar inserter 178.In another alternative, the cross bar 50 may be moved into the finalposition using either or a combination of a persuader 190 and a blockerinserter 192, as shown in FIGS. 12A-B. The persuader 190 may have agenerally tubular member 191 having a distal end 194 and a proximal end196. The tubular member 191 may be sized to fit over an integratedconnector 98 such that the integrated connector 98 is received insidethe tubular member 191, as shown in FIGS. 12A-B. A handle 198 may beconnected to the tubular member 191 towards its proximal end 196. Theblocker inserter 192 may be an elongate tool having a handle 204 at itsproximal end 206 and a blocker interface 200 at its distal end 202. Theblocker interface 200 may be shaped to engage a correspondingly shapedinterface 208 (such as a hexagonally shaped recess) on a blocker 52. Theblocker 52 may be an externally threaded component, similar to the setscrews 45 of the connecting elements 30 implanted in the pedicles, andthe threads 210 of the blocker 52 may be structured to engage thethreaded portion 118 towards the distal end 97 of the cannula 92 and thethreaded portion 120 of the cross bar receiving portion 110 of theconnector 48.

In one embodiment, the handle 198 of a persuader 190 may be grasped andmanipulated so that the tubular member 191 is fit over the proximal end101 of an integrated connector 98 and advanced distally towards thetransversely oriented cross bar 50. The distal end 194 of the tubularmember 191 may contact the cross bar 50 and push it distally towards andinto the final position within the receptacle 114 of the connector 48.

In another embodiment, a blocker inserter 192 may have a blocker 52placed onto the blocker interface 200 at its distal end 202, after whichthe blocker inserter 192 may be advanced distally between the blades 94of the integrated connector 98. When the blocker 52 reaches the threadedportion 118 of the cannula 92, the blocker inserter 192 may be rotatedto advance the blocker 52 along the threaded portion 118. Furtheradvancement of the blocker 52 may cause the threads 210 of the blocker52 to engage and advance along the threaded portion 120 of the connector48. The blocker 52 may be advanced in this manner until the cross bar 50is securely captured within the receptacle 114. Desirably, at some pointduring the distal advancement of the blocker 52, such as during theadvancement along the threaded portion 118 or along the threaded portion120, the blocker 52 may contact the cross bar 50 and push the cross bar50 distally towards and into the final position within the receptacle114.

In another embodiment of the present invention, both the persuader 190and the blocker inserter 192 may be used, as shown in FIGS. 12A-B. Forexample, the persuader 190 may be used to push the cross bar 50distally, as described above, until the cross bar 50 is at least withinthe threaded portion 118 of the cannula 92. After that, the blockerinserter 192 connected to the blocker 52 may be advanced, as describedabove, to push the cross bar 50 the remaining distance towards and intothe final position within the receptacle 114.

In some embodiments, the blocker inserter 192 may be constructed as atorque wrench, such that the torque applied by the blocker interface 200is limited to a pre-selected amount. In other embodiments, the blockerinserter 192 may not be so constructed, and a separate torque-limitingblocker inserter (not shown) may be provided. In either case, the finaltightening of the blocker 52 into the connector 48 so as to secure thecross bar 50 therein may be performed with a torque limiting tool. Sucha tool may be set to limit the tightening torque to, for example, 8 Nm(newton-meters).

The cross bar 50 may be released from the cross bar inserter 178, andthe cross bar inserter 178 may be removed from the body, at any pointafter the cross bar 50 is in a desired position within the body. Forexample, the cross bar inserter 178 may be removed before the cross bar50 is moved into the final position using either or both of thepersuader 190 and the blocker inserter 192. Alternatively, the cross barinserter 178 may remain attached to the cross bar 50 during the finalpositioning with the persuader 190 and the blocker inserter 192,preferably in a location out of the way of those tools.

After the various blockers 52 have been finally tightened to secure oneor more cross bars 50 within the connectors 48, any insertion tools thatremain positioned within the body (including the cross bar inserter 178,persuader 190, and blocker inserter 192) may be removed from the body.The cannula 92 may then be removed from the connector 48. For example,the blades 94 of the cannula may be separately disconnected from theconnector 48 and removed from the body. In an embodiment utilizing anintegrated connector 98, the blades 94 may be disconnected from theconnector 48 by breaking each of the blades 94 away from the connector48 at the frangible portions 96.

One method for breaking the blades 94 of the integrated connector 98away from the connector 48 is illustrated in FIG. 13. Such a method mayinclude separately engaging each blade 94 with a blade remover 212. Theblade remover 212 may be an elongate tool having a proximal end 214 anda distal end 216. The blade remover 212 may include a handle 218 at theproximal end 214 and may have a channel 220 formed therein open to thedistal end 216. The channel 220 may be constructed to receive a blade 94of an integrated connector 98 therein. The blade remover 212 may alsoinclude a spring clip 222 in communication with the channel 220 suchthat the spring clip 222 may securely engage a blade 94 when the blade94 is positioned within the channel 220, preferably in order to retainthe blade 94 within the blade remover 212 after the blade 94 has beendetached from the connector 48. The blade remover 212 may also include arelease mechanism (not shown) movably engaged within the channel 220 soas to eject the blade 94 from the channel 220 after the detached blade94 has been removed from the body. In one embodiment, the releasemechanism may include a slider received within a longitudinal trackalong the channel 220, such that distal movement of the slider will pushthe blade 94 out of the channel 220 at the distal end 216 of the bladeremover 212.

In use, the blade remover 212 is engaged to a blade 94 by sliding theblade remover 212 distally over the blade 94 until the blade is receivedwithin the channel 220. Using the handle 218, a user may pivot the bladeremover 212, and thus the blade 94 received therein, about the frangibleportion 96 until the frangible portion 96 fractures, thus disconnectingthe blade 94 from the connector 48. The blade remover 212 may then beremoved from the body, and desirably the spring clip 222 may retain theblade 94 within the blade remover 212 until the blade remover 212 isremoved from the body. After the blade remover 212 is removed from thebody, the detached blade 94 may be ejected from the channel 220 byactuating the release mechanism. The blade remover 212 may then be usedagain by repeating the above steps to remove other blades 94 from theconnectors 48.

Although, in the connectors 48 described herein, the rod receivingportion 108 is illustrated as being integrally formed with the cross barreceiving portion 110, in other embodiments of the connectors inaccordance with the present invention, the rod receiving portion may beseparately formed from the cross bar receiving portion, and both suchparts may be coupled together to form the connector. In one such anembodiment, the rod receiving portion and the cross bar receivingportion may be polyaxially coupled together.

Although the connectors 48 described herein are structured for directengagement with the rods 44, other embodiments of the connectors inaccordance with the present invention may be otherwise engageable withportions of the spinal fusion construct. For example, the connector maybe structured to straddle the cage 42 of a connecting element 30 whilethe connector is connected to the rod 44 on each side of the cage 42. Inanother example, the connector may not be engaged with the rod 44 atall, and may instead, for example, be structured to be directly affixedto the cage 42 of a connecting element 30.

The various components described herein are preferably constructed ofmaterials safe for use in the body. In one embodiment, many of thecomponents, including the components of the integrated connector 98, maybe constructed from a titanium alloy.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

The invention claimed is:
 1. A dilator for accessing a spinal fusion rodattached to a spine, comprising: a generally tubular body having aproximal end and a distal end, the generally tubular body defining apassageway therein extending along a longitudinal axis thereof such thata connector can be passed through the passageway from the proximal endto the spinal fusion rod positionable at the distal end; and anattachment structure at the distal end of the generally tubular body,the attachment structure being defined by a partially cylindrical recessextending across the distal end of the generally tubular body transverseto the longitudinal axis, such that the partially cylindrical recessintrudes into the distal end of the generally tubular body to therebydefine a concave cylindrical surface and an opposing opening open in adistal direction along the longitudinal axis, the partially cylindricalrecess being adapted to mate with the spinal fusion rod by advancing thespinal fusion rod into the opening in a proximal direction along thelongitudinal axis, such that the partially cylindrical recess deforms tosnap onto the spinal fusion rod and a circular cross section of thespinal fusion rod is received within the partially cylindrical recess ofthe attachment structure.
 2. The dilator of claim 1, wherein theattachment structure includes a slot to facilitate the deformation ofthe attachment structure when the attachment structure snaps onto thespinal fusion rod.
 3. A dilation system, comprising: the dilator asrecited in claim 1; and at least one inner dilator adapted to bereceived within the passageway of the dilator, the inner dilator beingadapted to spread tissue apart along a pathway to the location proximatethe spine before the dilator is advanced along the pathway.
 4. Thedilation system of claim 3, wherein a distal end of the inner dilator istapered.
 5. A dilator for accessing a location proximate a spine,comprising: a generally tubular body extending along a longitudinal axisbetween a proximal end and a distal end, the generally tubular bodydefining a first passageway therein extending along the longitudinalaxis; and an attachment structure adapted to mate with a percutaneousaccess device detachably connected to a connecting element forattachment to the spine, the percutaneous access device defining asecond passageway therein that extends proximally from the connectingelement, wherein the attachment structure is connected to the generallytubular body such that, when the attachment structure is mated with thepercutaneous access device, the first passageway defined by thegenerally tubular body is laterally spaced apart from the secondpassageway defined by the percutaneous access device.
 6. The dilator ofclaim 5, wherein the attachment structure is positioned alongside thegenerally tubular body between its proximal and distal ends.
 7. Thedilator of claim 6, wherein the connecting element is adapted to securea spinal fusion rod to the spine, and wherein the percutaneous accessdevice is detachably connected to the connecting element and extendsproximally therefrom out of the body.
 8. The dilator of claim 7, whereinthe percutaneous access device comprises two blades positioned adjacentto one another and defining an elongated cannula, and wherein theattachment structure extends laterally from the generally tubular bodyand receives the blades therein.
 9. The dilator of claim 8, wherein theattachment structure includes a plurality of receivers extendinglaterally from the generally tubular body, each of the receivers havinga respective channel therealong shaped to receive a respective bladetherein.
 10. A dilation system, comprising: the dilator as recited inclaim 5; and at least one inner dilator adapted to be received withinthe passageway of the dilator, the inner dilator being adapted to spreadtissue apart along a pathway to the location proximate the spine beforethe dilator is advanced along the pathway.
 11. The dilation system ofclaim 10, wherein a distal end of the inner dilator is tapered.